共查询到14条相似文献,搜索用时 78 毫秒
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黄大明柳小妮 宋百敏陈俊 Masae Shiyomi 王昱生 Shigeo Takahashi Yoshimichi Hori Yasuo Yamamura 《清华大学学报》2007,12(4):413-423
The vegetation spatial heterogeneity and ecological characteristics in different soil regions were analyzed by surveying the vegetation in 12 different soil regions of Inner Mongolia, China, including conifer- ous-broadleaf deciduous forests, shrub, grassland, and desert regions with 1122 large 2 cm × 2 cm quad- rats (actual size 30 km × 30 km, referred to as L-quadrat hereafter) in about 1.18 million km2. Each L- quadrat was divided into four small 1 cm × 1 cm quadrats (actual size 15 km × 15 km, S-quadrat). The vegetation was analyzed based on the beta-binomial distribution to describe the frequency of occurrence and spatial heterogeneity for each kind of vegetation. The weighted average of the heterogeneity of all vegeta- tion in the same soil region provides a measure of the soil regional landscape level heterogeneity which de- scribes the spatial complexity of the regional landscape composition of the existing vegetation. Comparison of the vegetation characteristics in the 12 soil regions shows that, the calcic gray soil has the highest average vegetation type per quadrat. The largest soil region is calcic chestnut soil and has the most vegetation types. Every soil region has its own dominant vegetation sequence which dominates in occurrence and dominant vegetation types which dominates in spatial heterogeneity. For the Inner Mongolian vegetation, the weighted average of the heterogeneity is 0.60 and the vegetation diversity index is 4.47. 相似文献
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LU JunGang XU RenJi ZHANG QingHua LIU JiYan LIAO ChunYang WEI FuSheng 《科学通报(英文版)》2009,54(19):3528-3535
Lung cancer incidence in Xuanwei and Fuyuan is extremely high. The air pollution, especially indoor airborne PAHs generated by burning smoky coals, has been considered as the most probable reason. The air pollution may affect drinking water and soil through dry and wet deposition. In this study, the concentrations of PAHs in water and soil samples from Xuanwei and Fuyuan were monitored to investigate the influence of atmospheric PAHs pollution on water and soil. No obvious PAHs pollution in water was found in these two areas, indicating that airborne PAHs have no apparent effect on the drinking water (well water). The smoky coal combustion from household and industry, such as the activities related to power plants, coking plants and chemical industries, is responsible for the soil PAHs pollution in these two areas. The soil pollution might be the reemission source and would pose long-term threat to the local environment and health of residents. 相似文献
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Biosorption of Cu(Ⅱ) and Pb(Ⅱ) by Auricularia polytricha 总被引:1,自引:0,他引:1
ZHANG Dan GAO Jianwei GAO Tingyan YING Yigao CHEN Hong 《武汉大学学报:自然科学英文版》2007,12(4):755-761
For searching biological material for heavy metal removal of waste-water, using macrofungus Auricularia polytricha as biosorbent for Cu^2+ and Pb^2+ removal was investigated. After shaking and biosorbing Cu^2+ and Pb^2+ in solution by biosorbents, the filtrates were tested by AAS and the adsorbed quantity of Cu^2+ and Pb^2+ was calculated. The biosorbents were effective in removal of Cu^2+ and Pb^2+ on the biosorbents that showed a high- est value around pH 5-6. The biosorption rate of Cu^2+ and Pb^2+ on A. polytricha biomass decreased with increasing the initial concentration of Cu^2+ and Pb^2+ in the medium. The biosorption of Cu^2+ and Pb^2+ on the biomasses follows pseudo-second order kinetics. The determined maximum biosorption capacities presented by the fungus biomass were 3.34 and 13.03 mg·g^-1 dry weight for Cu^2+ and Pb^2+, respectively by the biosorption equilibrium with Langmuir adsorption isotherm. According to the whole data analysis in each experiment of studying Cu^2+ and Pb^2+ biosorption including condition factors and adsorption isotherm, the adsorbed capacity of Pb^2+ by A. polytricha biomass was bigger than Cu^2+. The biosorption by A. polytricha was most effective when pH 5-6. The biosorbents are suitable for low Cu^2+ and Pb^2+ concentration waste-water, especially for Pb^2+ removal. 相似文献
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城市大气重金属(Pb,Cd,Cu,Zn)污染及其在植物 … 总被引:15,自引:0,他引:15
通过对烟台市区不同大气污染区域绿化植物叶片中重金属Pb,Cd,Cu,Zn富积量和大气与土壤中相应重金属的含量研究分析发现,植物叶片中重金属Pb,Cu,Zn的富积与大气中Pu,Cu,Zn的相对含量呈显著的正相关,而植物叶片中Cd的富积量与大气中重金属的相对含量相关不显著,所研究的4种重金属的在植物叶片中的富积量与其生长土壤中的重金属的含量无相关性,研究证明,在所调查的5种市区绿化植物中以园叶片对大气 相似文献
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Concentration level and distribution of polycyclic aromatic hydrocarbons in soil and grass around Mt. Qomolangma, China 总被引:2,自引:0,他引:2
WANG XiaoPing YAO TanDong CONG ZhiYuan YAN XinLiang KANG ShiChang ZHANG Yong 《科学通报(英文版)》2007,52(10):1405-1413
High mountains may serve as a condenser for persistent organic pollutants. In the present study, soil and grass samples from Mt. Qomolangma region, China were collected from 4600 to 5620 m a.s.I and were analyzed for polycyclic aromatic hydrocarbons (PAHs) to determine if they are concentrated at colder, more elevated sites and to evaluate their possible resources and fractionation. The total PAHs concentration in soil samples was 〈 600 ng g^-1, the critical value to differentiate PAHs levels in remote and urban regions. This implied the PAHs levels at Mt. Qomolangma are relatively low and what one might expect in such a remote region of the world. These low values may represent a soil background for mid-latitude Northern Hemisphere soils away from the direct influence of an anthropogenic source. As for the distribution pattern, the low molecular weight PAHs were prone to accumulate at higher altitude, while the high molecular weight PAHs inversely related or unrelated with elevation. Based on high concentration of phenanthrene at elevated sample site and the ratios of individual PAHs, we deduced that home-heating combustion and vehicle emission may result in the constitution trait of PAHs in this mountain region. Monsoon traveling over India, Pakistan and other countries with dense population may carry contaminant to Mt. Qomolangma region. 相似文献
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ZHANGJian-guo YANGYong-hong LIUShu-zhen 《武汉大学学报:自然科学英文版》2005,10(4):635-640
Based on the analysis of existing relevant research result, a theoretical basis for the defining freeze-thawerosion zones of Qinghai-Tibet Plateau was been put forward, and a equation for calculating the altitude of the lower bound of the freeze-thaw erosion zones of Qinghai-Tibet Plateau was been established in this paper. Moreover, the freeze-thaw erosion zones in Tibet was been identified by using Geographical Information System (GIS) software. Next, based on thecomprehensive analysis of impact factors of freeze-thaw erosion, this paper chooses annul temperature range, slop and vegetation as three indexes, works out the criteria for relative classification of freeze-thaw erosion, and realizes the relative classification of the freeze-thaw erosion in Tibet under the support of GIS software. Then, a synthetic assessment of freeze-thaw erosion in Tibet was been done according to the relative classification result. 相似文献
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Lu Wenzheng 《中国工程科学》2004,2(2):12-14
The tectonic setting of the west region of the Reserved Area of the International Seabed Authority is the same as that of China Pioneer Area. They have similar characteristics of topography and nodule distribution. To research and analyse the characteristics and control factors of nodule distribution can help the establishment of a geological model and the assessment of the polymetallic nodule resource. From the year of 1991 till 2000 COMRA (China Ocean Mineral Resource Research and Development Association) carried out phase 1 and 2 of the exploration and resource assessment project of polymetallic nodules in China Pioneer Area. The features of topography and geology, and the distribution of polymetallic nodules and control factors have been clearly understood. The results show that the formation and types and spatial features of abundance and grade of nodules resulted from several factors, the tectonic features (volcanism and faulting)and seafloor topography play an important role in the geological process of the formation of polymetallic nodules. 相似文献
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YE Junwei ZHANG Ping YE Kaiqi YE Ling YANG Guangdi WANG Yue 《科学通报(英文版)》2006,51(14):1682-1686
Hydrothermal reactions of Cu (Ⅱ) acetate, 2,2'-bipyridyl (bpy) with 5-nitroisophthalic acid (H2NIPH) resulted in a new coordination polymer [Cu(NIPH)(bpy)] 1. Single crystal X-ray diffraction experiment indicates that 1 possesses a single helixlike chains, of which Cu atoms are coordinated by NIPH ligands and bpy ligands. Compound 1 crystallizes in the space group P2( 1)/c, a = 0.955(19) nm, b = 1.259(3) nm, c = 1.3737(3) nm, ,6= 95.13(3)°, V= 1.6455(6) nm^3 and Z = 4. The TGA analysis shows that 1 has no remarkable weight loss up to 284℃, as a result of its high thermal stability. Magnetic measurements indicate an antiferromagnetic behavior of compound 1. 相似文献
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It is important to research the rules about accumulation and distribution of arsenic and cadmium by tea plants, which will give us some scientific ideas about how to control the contents of arsenic and cadmium in tea. In this study, by field investigation and pot trial, we found that mobility of arsenic and cadmium in tea plants was low. Most arsenic and cadmium absorbed were fixed in feeding roots and only small amount was transported to the above-ground parts. Distribution of arsenic and cadmium, based on their concentrations of unit dry matter, in tea plants grown on un-contaminated soil was in the order: feeding roots〉stems=main roots〉old leaves〉young leaves. When tea plants were grown on polluted soils simulated by adding salts of these two metals, feeding roots possibly acted as a buffer and defense, and arsenic and cadmium were transported less to the aboveground parts. The concentration of cadmium in soil significantly and negatively correlated with chlorophyll content, photosynthetic rate, transpiration rate and biomass production of tea plants. 相似文献
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Microbial activity and community diversity in a variable charge soil as affected by cadmium exposure levels and time
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Effects of cadmium (Cd) on microbial biomass, variable charge soil (Typic Aquult) using an incubation study activity and community diversity were assessed in a representative Cadmium was added as CdCNO3)2 to reach a concentration range of 0-16 mg Cd/kg soil. Soil extractable Cd generally increased with Cd loading rate, but decreased with incubation time. Soil microbial biomass was enhanced at low Cd levels (0.5-1 mg/kg), but was inhibited consistently with increasing Cd rate. The ratio of microbial biomass C/N varied with Cd treatment levels, decreasing at low Cd rate (〈0.7 mg/kg available Cd), but increasing progressively with Cd loading. Soil respiration was restrained at low Cd loading (〈1 mg/kg), and enhanced at higher Cd levels. Soil microbial metabolic quotient (MMQ) was generally greater at high Cd loading (1-16 mg/kg). However, the MMQ is also affected by other factors. Cd contamination reduces species diversity of soil microbial communities and their ability to metabolize different C substrates. Soils with higher levels of Cd contamination showed decreases in indicator phospholipids fatty acids (PLFAs) for Gram-negative bacteria and actinomycetes, while the indicator PLFAs for Gram-positive bacteria and fungi increased with increasing levels of Cd contamination. 相似文献
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Differential generation of hydrogen peroxide upon exposure to zinc and cadmium in the hyperaccumulating plant specie (Sedum alfredii Hance) 下载免费PDF全文
Sedum alfredii Hance has been identified as zinc (Zn) and cadmium (Cd) co-hyperaccumulator. In this paper the relationships of Zn or Cd hyperaccumulation to the generation and the role of H2O2 in Sedum alfredii H. were examined. The results show that Zn and Cd contents in the shoots of Sedum alfredii H. treated with 1000 μmol/L Zn^2+ and/or 200 μmol/L Cd^2+ increased linearly within 15 d. Contents of total S, glutathione (GSH) and H2O2 in shoots also increased within 15 d, and then decreased. Total S and GSH contents in shoots were higher under Cd^2+ treatment than under Zn^2+ treatment. However, reverse trends of H2O2 content in shoots were obtained, in which much higher H2O2 content was observed in Zn^2+ -treated shoots than in Cd^2+-treated shoots. Similarly, the microscopic imaging of H2O2 accumulation in leaves using H2O2 probe technique showed that much higher H2O2 accumulation was observed in the Zn^2+-treated leaf than in the Cd^2+ -treated one. These results suggest that there are different responses in the generation of H2O2 upon exposure to Zn^2+ and Cd^2+ for the hyperaccumulator Sedum alfredii H. And this is the first report that the generation of H2O2 may play an important role in Zn hyperaccumulation in the leaves. Our results also imply that GSH may play an important role in the detoxification of dissociated Zn/Cd and the generation of H2O2. 相似文献
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通过对北京地区物流企业(园区)人才需求进行调研,阐述了北京市物流企业(园区)对物流人才的需求情况,提出了有关今后物流人才培养和物流行业建设的建议。 相似文献